Stalk Nitrate Test Results for New York Corn Fields from 2010 through 2024

Sanjay Gami¹, Juan Carlos Ramos Tanchez¹, Mike Reuter², and Quirine M. Ketterings¹

¹Cornell University Nutrient Management Spear Program (NMSP) and ²Dairy One

Introduction

            The corn stalk nitrate test (CSNT) is an end-of-season evaluation tool for N management for corn fields in the 2nd or more years after a sod. It allows for identification of situations where more N was available during the growing season than the crop needed (CSNT>2000 ppm). Results can vary from year to year but where CSNT values exceed 3000 ppm for two or more years, it is highly likely that N management changes can be made without impacting yield. 

Findings 2010-2024

            In 2024, 47% of all tested fields had CSNT-N greater than 2000 ppm, while 37% were over 3000 ppm and 28% exceeded 5000 ppm (Table 1). In contrast, 20% of the 2024 samples were low in CSNT-N. Two years of CSNT monitoring is recommended before making management changes unless CSNT’s exceed 5000 ppm, in which case one year of data is sufficient.
            Some of the variability in CSNT distribution over the years may be reflect differences in growing season (Figure 1). The percentage of samples testing excessive in CSNT-N across 2010-2024 was most correlated with the total precipitation in May-June with droughts in those months translating to a greater percentage of fields testing excessive. The year 2024 was classified as normal based on these criteria although some areas experienced drought conditions for parts of the season, possibly contributing to a higher percentage of stalks testing excessive in CSNT.

            Within-field spatial variability can be considerable in New York, requiring (1) high density sampling (equivalent of 1 stalk per acre at a minimum) for accurate assessment of whole fields, or (2) targeted sampling based on yield zones, elevations, or soil management units. The Adaptive Nitrogen Management for Field Crops in New York lists targeted within-field CSNT sampling as one of five end-of-season evaluation tools. Samples received in more recent years may also reflect more targeted field sampling. 

A bar graph.
Figure 1: In drought years more samples test excessive in CSNT-N while fewer test low or marginal. The last 15 years included six drought years (2012, 2016, 2018, and 2020 through 2023), three wet years (2011, 2013, and 2017), and five years labelled normal (2010, 2014, 2015, 2019, and 2024) determined by May-June rainfall (less than 7.5 inches in drought years, 10 or more inches in wet years). Weather data are state averages; local conditions may have varied from state averages.

            Because crop and manure management history, soil type and growing conditions all impact CSNT results, conclusions about future N management should consider the events of the growing season. This includes weed and disease pressure, lack of moisture in the root zone in drought years, lack of oxygen in the root zone in wet years, and any other stress factor that can impact crop growth and N status. 

Relevant References

   Instructions for CSNT Sampling: http://nmsp.cals.cornell.edu/publications/StalkNtest2016.pdf.
.  Agronomy Factsheets #31: Corn Stalk Nitrate Test (CSNT); #63: Fine-Tuning Nitrogen Management for Corn; and #72: Taking a Corn Stalk Nitrate Test Sample after Corn Silage Harvest. http://nmsp.cals.cornell.edu/guidelines/factsheets.html.
.  Adaptive Nitrogen Management for Field Crops in New York (2025): http://nmsp.cals.cornell.edu/publications/extension/AdaptiveNitrogenManagement2025.pdf

Acknowledgments

We thank the farmers and farm consultants that sampled their fields for CSNT over the years.

For questions about these results contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/

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Profitability of contrasting organic management systems from 2018-2021 in the Cornell Organic Cropping Systems Experiment

Kristen Loria1, Allan Pinto Padilla2, Jake Allen1, Christopher Pelzer1, Sandra Wayman1, Miguel I. Gómez2, Matthew Ryan1

1School of Integrative Plant Science, 2Charles H. Dyson School of Applied Economics and Management, Cornell University, Ithaca, NY 14853.

About the Cornell Organic Cropping Systems Experiment

The Cornell Organic Cropping Systems (OCS) experiment was established in 2005 at the Musgrave Research Farm in Aurora, New York to serve as a living laboratory for organic field crop management systems and provide practical insights to farmers. This ongoing long-term experiment compares four management systems along a dual spectrum of external inputs and soil disturbance over a multi-year crop rotation. An advisory board consisting of a dedicated group of organic farmers provides guidance on management decisions. The four systems are compared in terms of several sustainability indicators including yield, profitability, soil health and greenhouse gas emissions.

Both external input and soil disturbance gradients of the four treatment systems range from an extensive approach (low input) aimed at maximizing profitability by reducing costs via efficient resource use, to an intensive approach (high input), aimed at maximizing profitability by maximizing yield. Risk associated with low input management includes reduced crop production from inadequate soil fertility or weed competition, which can lead to decreased returns despite low input costs. Risk associated with high input management include diminishing returns where productivity increases are insufficient to justify additional cost.

The four management systems of OCS are: 1) High Fertility (HF), 2) Low Fertility (LF), 3) Enhanced Weed Management (EWM), and 4) Reduced Tillage (RT). In 2018, the crop rotation was modified from a three-year rotation to a  four-year rotation based on advisor input.: This article includes an economic analysis of the complete four-year crop rotation cycle from 2018-2021, which consisted of: 1) triticale / red clover, 2) corn / interseeded cover crop mix, 3) summer annual forage mix / cereal rye cover crop, 4) soybean (Figure 1).

Figure 1. Four-year crop rotation for the OCS phase 2018-2021.

Looking back: key takeaways from past OCS cycles

Caldwell et al. (2014) compared the yields and the profitability during and after the initial phase of organic transition in OCS following two three-year rotation cycles (corn-soybean-winter spelt/red clover) from 2005-2010. The first three years were considered as transitional production years in which crops could not be sold as certified organic, while crops produced from 2008 to 2010 could be sold as such. They used flexible interactive crop budgets to calculate relative net returns based on crop yields, tillage, weed management and fertility practices and, after the three-year transition period, compared relative net returns of organic production with concurrent organic price premiums to Cayuga County yield averages with conventional crop production inputs and prices. With a 30% organic price premium, the relative net return of organic production in all systems except RT was positive. The RT system was excluded from most analyses due to major challenges with experimental ridge-till practices resulting in decreased crop competitiveness. For both corn and soybean phases averaged across entry points, relative net return in the HF system was significantly lower than LF or EWM, due to higher input costs without corresponding higher yields in the HF system. For the spelt phase averaged across entry points, relative net return was higher in HF than LF and EWM (though not significantly so), with increased input cost in the HF system corresponding with a yield increase. The HF system led to higher weed biomass over time than the EWM and LF systems.

Trial design and system differences

The Cornell Organic Cropping Systems experiment uses a split-plot randomized complete block design with four blocks. The main plot treatments are the four management systems, whereas subplot treatments are two crop rotation entry points (A and B) . Entry points A and B represent different phases of the crop rotation. For example, in 2018 entry point A was planted to triticale while entry point B was planted to soybean.

Treatment systems are arranged along a fertility gradient as well as a soil disturbance gradient (Figure 3). For triticale, summer forage, and corn, the HF system had a 50% higher fertilization rate than RT and EWM. LF received fertilizer rates 50% lower than RT and EWM on the same crops. Intermediate fertilizer rates were applied to both EWM and RT. With respect to soil disturbance, EWM received additional weed management operations in several crops, while RT and LF incorporated an organic no-till soybean phase. Overall number of primary tillage events was not substantially different between systems, though mechanical cultivation was reduced in the soybean phase for RT and LF.

Figure 2. Contrasting management approaches in four systems.

Crop yields across management systems

No matter the management system, crop yield is a key component of profitability. Yields across all four years of the cycle comprising five harvested crops are summarized below. Ryelage was only harvested in EWM and HF systems as the cereal rye cover crop was rolled-crimped for no-till soybean in LF and RT systems. Triticale was grown as a grain crop in EWM and HF and taken for forage in the LF and RT systems. Organic no-till practices were implemented in RT and LF systems only, with soybean planted into tilled soil in HF and EWM. In entry point A soybean yields were comparable across systems, but in entry point B organic no-till soybean yields were nearly half of cultivated yields, likely due to dry conditions in the soybean phase in 2018.

Table 1. Mean yields for all harvested crops across four management systems and crop rotation entry point from 2018-2021. Within an entry point, systems sharing a letter were not significantly different (p < 0.05). Means were not compared between entry points. Triticale in RT and LF systems was harvested as forage (lbs DM/ac) while in HF and EWM it was harvested as grain (lbs/ac). Means were not compared.

Net return of management systems

Net return subtracts total variable costs (TVC) of production (inputs + labor + equipment-associated costs) from gross income (crop yield x price). Prices for corn and soybean were obtained from the USDA organic grain report (USDA National Organic Grain and Feedstuffs Report, February 4, 2022). As commodity price references for triticale grain, cereal rye forage and summer annual forage were unavailable, prices were based those typically fetched for organic forage in NY (MH Martens and P Martens, personal communications, 2022). All operation-related costs were taken from Pennsylvania’s 2022 Custom Machinery Rates (USDA NASS 2023). To correct the absence of an inflation adjustment, crop prices and input costs used in this study were converted to real values using the U.S. Consumer Price Index (CPI), with 2016 as the reference year.

All values are denominated in U.S. dollars and represent the average annual revenue, production costs, and net return over four years. In the case of crop rotation entry point A, the LF cropping system exhibited the lowest Total Variable Cost (TVC). Conversely, the HF system had the highest TVC, which despite higher grain and forage yields, resulted in lower net return than LF, EWM and RT systems (Figure 4).

Overall, across four years of the crop rotation and in both crop rotation entry points (i.e., temporal replications of the trial) the EWM system maximized net return via intermediate fertility rates and relatively high yields, though the HF system yielded higher in both entry points Net return for RT and LF systems was more variable between crops and entry points, possibly indicating higher weather-related risk associated with those system approaches, i.e. reliance on cover crops for fertility in LF, and use of organic no-till management for LF and RT (Figure 4).

Figure 4. Comparison of net return and components across four systems in entry point A.

In entry point A, LF demonstrated higher net return than both HF and RT despite lower yields due to reduced input costs. Net return in RT narrowly surpassed HF due to lower input costs as well. In entry point B, LF ranked lowest in net return due to low grain yields across the rotation. HF ranked second and RT ranked third, with RT characterized by intermediate to low yields with intermediate input costs.

Figure 5: Comparison of net return and components across four systems in entry point B.

When net return of each management system is summarized by entry point, high variability in profitability was observed across entry points, largely due to yield differences between growing seasons of the same crop. Because management was nearly identical for each crop within each system across entry points, temporal variation in net return can be attributed to yield response from seasonal environmental or climatic factors either directly or in interaction with management. This highlights the complexity of systems experiments given year-to-year variation (Figure 6).

Figure 6: Net return comparison of all four cropping systems and two entry points.

Conclusions

Differences in yield and subsequent net return between systems varied significantly across entry points, making it difficult to draw conclusions on the most profitable system overall. However, the HF system had the lowest net return across entry points, indicating that input levels were likely higher than optimum and yield gains to justify increased inputs were not realized. EWM had the highest net return across entry points, indicating that intermediate levels of fertility combined with additional cultivation passes in the row crop phases and full tillage soybean production “paid off” as a management strategy, with increased labor or fuel costs outweighed by increased yields. Of course, this assumes availability of labor required which may be out of reach for some farms, and can be challenged by finite weather-related windows conducive to field operations.

Variability in net return between entry points was particularly high for the LF and RT systems, largely driven by yield variation in the soybean phase between temporal replications. For entry point B, intermediate corn yields and low organic no-till soybean yields drove low profitability in LF, while relatively high corn yield in RT partially made up for low organic no-till soybean yield. This variation in soybean yield highlights a challenge with an organic no-till management approach that dry conditions can reduce yields to a greater extent compared to a tillage-based approach. However, in an extremely wet year where adequate weed control was not possible, no-till management may pay off.

By accounting for system profitability only, this article does not consider other tradeoffs between systems such as soil health outcomes or greenhouse gas emissions from contrasting management, additional sustainability metrics to evaluate organic production system success.

References

Caldwell, B; Mohler, CL; Ketterings, QM; and DiTommaso, A. (2014). Yields and profitability during and after transition in organic grain cropping systems. Agronomy Journal, 106(3):871–880.

Gianforte, L personal communication. 2022.

Jernigan, A. B., Wickings, K., Mohler, C. L., Caldwell, B. A., Pelzer, C. J., Wayman, S., and Ryan, M. R. (2020). Legacy effects of contrasting organic grain cropping systems on soil health indicators, soil invertebrates, weeds, and crop yield. Agricultural Systems, 177:102719.

USDA National Organic Grain and Feedstuffs Report, February 4 2022. Agricultural Marketing Service.

Martens, MH personal communication. 2022.

Martens, P personal communication. 2022.

Pennsylvania’s 2022 Machinery Custom Rates. USDA NASS.

For more results from the Cornell Organic Systems Experiment visit the Sustainable Cropping Systems Lab website.

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New End-Of-Season Assessment Tool for Nitrogen Management of Corn Silage

Agustin J. Olivo1, Olivia F. Godber1, Kirsten Workman1,2, Karl J. Czymmek1,2, Kristan F. Reed1, Daryl V. Nydam3, Quirine M. Ketterings1

1Department of Animal Science, 2PRO-DAIRY, 3Department of Public and Ecosystem Health Cornell University, Ithaca, NY United States 

Introduction

            Effective nitrogen (N) management is an essential aspect of productivity and sustainability of corn silage production for dairies. In New York (NY), end-of-season evaluations that consider indicators like N balance (N supply – N removal) and ratio of N removal to N supply can be implemented to assess nutrient use efficiency. Comparing these results with feasible outcomes can help farmers identify opportunities to refine N management over time, and support field experimentation through the NY adaptive N management process. To identify target values for these indicators, characteristics of 994 corn silage field observations across eight NY dairies, together with land grant university guidelines for N management were used to create the “Green Operational Outcomes Domain” (GOOD) assessment framework. The GOOD combines feasible target values for field-level N balances, N removal/N supply, and an indicator related to manure inorganic N utilization efficiency. Indicators were derived using the method outlined in Agronomy Factsheet 125.

Key findings

The GOOD was defined by a 50% minimum N removal/N supply and a 142 lbs/acre maximum balance

A line graph depicting N balances and the "Green Operational Outcomes Domain."
Fig. 1. Feasible outcome values for maximum tolerable N balance and minimum N removal/N supply that define the GOOD framework.

            The GOOD framework was defined by comparing field N removal and available N supply (Fig. 1). Fields performing inside the GOOD (green area in Fig. 1) have an N removal/N supply that is at least 50%, and a field N balance of 142 lbs N/acre or less. The latter was defined based on the maximum balance that fields in the present dataset would display if managed according to land grant university guidelines. The GOOD was set to identify fields with large N balances and low efficiencies in the context of adaptive N management, without restricting application rates to less than annual P crop removal.

Average farm performance remained within the GOOD, but with large variability

            When considering actual farm management practices (“achieved” indicators) across all 994 fields, 66% of observations were within the GOOD and 34% outside. However, there was large variability across the eight farms evaluated.  The percentage of fields outside the GOOD ranged from only 1% for one farm (Fig. 2 left) and up to 54% for another farm (Fig. 2 right). The annual averages for achieved available N balance on all farms ranged between 4 and 192 lbs N/acre, and for N removal/available N supply between 38% and 95%.

Two line graphs describing the relationship between farm animal density and N balances.
Fig. 2. Nitrogen (N) removal and achieved available N supply as calculated from farm management data for corn silage fields of two different dairy farms. Percentages at the top of each graph represent the percentage of fields inside (green, left), and outside (red, right) the green operational outcomes domain (GOOD). Yellow diamonds represent the area-weighted average performance across all fields data was collected for in each farm.

Manure N use was efficient in this dataset, but with opportunities for refinement

            Forty-six percent of observations had spring manure injection or surface application followed by incorporation, whereas 32% received manure application but manure inorganic N contributions were zero (manure was either applied in fall, or in spring with no incorporation within five days). Twenty-six percent of observations were both within the GOOD and had manure inorganic N contributions larger than zero. This shows an overall efficient use of N for corn silage production. For 20% of the observations, manure injection or incorporation in the spring did take place, but the fields fell outside of the GOOD, reflecting opportunities to reallocate a portion of the nitrogen applied to other fields.

Additional graphical tools and indicators complement the GOOD framework well

A graph describing the relationships between yield and balances.
Fig. 3. Graphical tool displaying field achieved N balance vs corn silage yield, in the context of the feasible maximum tolerable N balance (142 lbs N/acre) and farm average yield. Q = quadrant.

            A series of additional graphical tools and numerical indicators were created to provide farms with more information to identify opportunities to refine N management in corn silage production. For example, one tool helps to identify fields with low yields and high N balances (Q3 in red, Fig. 3). These fields can represent the first target when attempting to refine N management in corn silage.

Conclusions

            The GOOD framework is introduced as an end-of-season assessment tool for farms to identify corn silage fields with large N balances and low N removal/N supply. This can be used in the context of the NY adaptive N management process, and/or to identify opportunities for N management refinement over time. On the latter, this study showed that the strategies with largest potential for refining N management and meeting the GOOD feasible targets included reducing N inputs, evaluating non-N yield barriers (e.g. drainage, pests) for fields with low yields and high balances, crediting N contributions from sod, and increasing manure N utilization efficiency (with spring injection or incorporation) and adjusting rates accordingly.

Full citation

            This article is summarized from our peer-reviewed publication: Olivo, A.J., O.F. Godber, K. Workman, K.J. Czymmek, K. Reed, D.V. Nydam, and Q.M. Ketterings (2024). Doing GOOD: defining a green operational outcomes domain for nitrogen use in NY corn silage production. Field Crops Research. https://doi.org/10.1016/j.fcr.2024.109676.

Acknowledgements

            We thank farmers and their certified crop advisors who shared farm data. This research was funded by a USDA-NIFA grant, funding from the Northern New York Agricultural Development Program (NNYADP), and contributions from the New York Corn Growers Association (NYCGA) managed by the New York Farm Viability Institute (NYFVI), and the Department of Animal Science, Cornell University. For questions about these results, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

Icons for the Nutrient Management Spear Program, Cornell University, Cornell CALS, and PRO-DAIRY

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Enhancing nitrogen management in corn silage: insights from field-level nutrient use indicators

Agustin J. Olivo1, Kirsten Workman1,2, Quirine M. Ketterings1

1 Department of Animal Science, Cornell University, Ithaca, NY, United States; 2PRO-DAIRY, Department of Animal Science, Cornell University, Ithaca, NY, United States

Introduction

              Optimizing nitrogen (N) management in corn silage production can help improve farm profitability while reducing potential environmental impacts derived from N losses in dairy farms. One strategy to monitor and improve nutrient management at the field level is the calculation of end-of-season field balances, the difference between nutrients supplied to the crop, and what is removed with harvest. Ideal field-level N balances are positive, but not excessively large.

Fig. 1. Nitrogen pools considered for N supply and N uptake when calculating field-level N balances.

              To assess the use of field N balances as an evaluation tool, field-level N balances (N supply – N uptake) and associated N use indicators were derived for 994 field observations from eight NY dairy farms across NY. Available and total N balances per acre, which differed only in the fraction of manure N accounted for (plant-available N or total N), yield-scaled N balances, and N uptake/N supply were calculated (Fig. 1).

Key findings

Nitrogen use indicators varied widely

              The median balance across all fields was 99 lbs/acre for available N and 219 lbs/acre for total N. Excluding soil N contributions reduced these medians to 26 lbs/acre for available N and 145 lbs/acre for total N. Median N uptake/N supply were 0.60 (available N) and 0.41 (total N). Balances varied by farm, ranging from 41 to 145 lbs/acre for available N and from 126 to 338 lbs/acre for total N (Fig. 2).

Two bar graphs.
Fig. 2. Relative frequency distributions for available nitrogen (N) balances per ac (A), and total N balances per ac (B), for all observations across farms and years.

Nitrogen supply considerably affected N use indicators

              Nitrogen supply was a bigger driver for N use indicators than N uptake (Fig. 3), suggesting that decisions on N inputs influence N use indicators more than yield itself. Larger balances were associated with high N supply and low-yielding fields, indicating that for those fields factors other than N supply limited yield. These could be in-season factors that prevent a field from achieving its yield potential (such as extreme weather events and pest problems), or (semi) permanent limitations (such as shallow depth to bedrock, subsurface compaction, and drainage issues) not acknowledged in N application planning.

Manure-N availability impacted N use efficiency

              The database showed a wide range of manure and fertilizer N supply to fields. Available manure organic and inorganic N played the largest roles in explaining the variability of N use indicators, with available N balances increasing with an increase in manure N supply. The study showed a 0.2 unit decrease in fertilizer N application on average in corn fields, with a 1 unit increase in available N from manure. This suggests that manure is valued as an N source, but its N content is not credited to the full extent possible, resulting in larger N balances at the end of the season.

Scatter plot.
Fig. 3. Available nitrogen (N) balances per acre, as related to N uptake and available N supply. Each data point represents a field*year observation in the database.

Sod-N crediting impacted N use efficiency

              First year corn fields showed reduced fertilizer and manure N applications than 2nd through 4th year fields (Fig. 4). Average available N balances (black dots in Fig. 4) for 1st year corn were, however, slightly larger than for fields with no sod N credits, suggesting opportunities for further reductions in nutrient allocation to 1st year corn.

A bar graph.
Fig. 4. Area-weighted average available nitrogen (N) from fertilizer and manure applications (colored bars), across all farms and years and for different stages of the crop rotation. Blue numbers (line one) on top of the graph represent number of observations in each category, and green numbers (line two), the area-weighted average N credits from sod for observations in each rotation stage. Black bolded numbers on top of each bar represent the sum of the area-weighted average available N from fertilizer and manure. COS1, COS2, COS3 = first, second and third crop year of corn silage after sod.

Farm animal density was associated with N use indicators

              At the whole-farm level, N balances per acre were positively related to animal density (animal units per acre) and impacted by farm crop rotations and within-farm allocation of manure N (Fig. 5).

Fig. 5. Relationship between farm animal density and (A) area-weighted farm averages for available nitrogen (N) balance, and (B) total N balance. Dotted horizontal gray lines represent the area-weighted average for each dependent variable across farms and years. AU = animal unit = 1,000 lbs of live animal weight.

Conclusions

              Nitrogen supply impacted N balance indicators more than N uptake (yield) and N balances tended to increase with larger farm animal density. Adjusting N supply based on realistically attainable yield, fully crediting manure and sod N contributions, improving manure inorganic N utilization efficiency, optimizing animal density, and/or exporting manure can aid in improving field N use indicators over time.

Full citation

              This article is summarized from our peer-reviewed publication: Olivo A.J., K. Workman, and Q.M. Ketterings (2024). Enhancing nitrogen management in corn silage: insights from field-level nutrient use indicators. Frontiers in Sustainable Food Systems 8. https://doi.org/10.3389/fsufs.2024.1385745.

Acknowledgements

              We thank farmers and their certified crop advisors who shared farm data. This research was funded by a USDA-NIFA grant, funding from the Northern New York Agricultural Development Program (NNYADP), and contributions from the New York Corn Growers Association (NYCGA) managed by the New York Farm Viability Institute (NYFVI), and the Department of Animal Science, Cornell University. For questions about these results, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

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Corn Stunt: A New Disease and a New Insect Vector for New York State

Gary C. Bergstrom

School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY 14853

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The presence of the corn stunt spiroplasma was confirmed in corn fields in four non-contiguous New York Counties (Erie, Jefferson, Monroe, and Yates) in October 2024.  The causal agent of corn stunt, Spiroplasma kunkelii, belongs to a specialized class of bacteria known as mollicutes which also includes phytoplasmas. Spiroplasma cells lack walls, and they have a short, spiral shape. They live an obligate lifestyle, i.e., they survive and reproduce only in living leafhopper hosts and in the phloem sieve elements of specific plant hosts. The pathogen that causes corn stunt is transmitted by the corn leafhopper, Dalbulus maidis, also not documented previously in New York (Figure 1). That status changed this October as individuals of D. maidis were caught on a yellow sticky trap in Jefferson County. One captured leafhopper was confirmed by molecular tests to be infected by S. kunkelii. This is the first documentation of the corn leafhopper and of S. kunkelii in both corn leaves and corn leafhoppers in New York.

Figure 1. Corn leafhopper
Figure 1. Corn leafhopper, Dalbulus maidis, the insect vector of corn stunt spiroplasma, is characterized by two prominent dark dots between its eyes and a deeply imbedded V-pattern on its upper thorax. Photo courtesy of Dr. Ashleigh Faris, Oklahoma State University.

How is the spiroplasma transmitted and spread?

The corn leafhopper, D. maidis, can acquire spiroplasma through its probing mouthparts in less than an hour of feeding in phloem tissues of infected corn plants, but it can take up to two weeks of spiroplasma replication in the leafhopper’s body before the insect can then transmit the spiroplasma into the phloem of healthy corn plants. Symptoms don’t generally appear until about a month after plants have been infected. The most severe symptoms are the result of infection at early corn growth stages (from VE to V8). An infected leafhopper can transmit spiroplasma to many nearby plants and can also be blown by air currents and deposited into distant corn fields.

Where did the leafhopper and spiroplasma in New York come from?

Corn stunt is a disease complex first described nearly 80 years ago in the Rio Grande Valley of Texas. Spiroplasma kunkelii is the principal pathogen causing corn stunt. However, other pathogens, either alone or in combination, also can cause corn stunt; these pathogens include the maize bushy stunt phytoplasma, the maize rayado fino virus, and the maize striate mosaic virus. Leaf samples from New York have been archived for later testing for these additional pathogens. Over past decades, there have been observations of corn stunt symptoms in several southern and eastern states but epidemics of corn stunt with well documented isolation of S. kunkelii have been primarily in Texas, Florida, and California. In recent years, corn stunt has occurred as a yield-reducing disease primarily in Mexico, Central and South America, particularly in Argentina and Brazil. The principal vector, the corn leafhopper, can be transported long distances by air currents and carries the pathogen within it. While there is no direct proof, it is very likely that long-distance atmospheric transport of the corn leafhopper into the Midwest and Northeast in 2024 was aided by storm systems that moved north from southern states.

What are the symptoms of corn stunt?

Corn stunt symptoms present similarly to other stresses in corn, including drought, soil compaction, and phosphorous deficiency. Leaf blades and sheathes can show white or yellow stripes (loss of chlorophyl) or red or purple streaks (anthocyanin pigments) and plants may show premature senescence (but without stalk rot) (Figure 2). Corn stunt varies from several common stressors in that plants can show significant stunting and ear abnormalities such as poorly filled ears, no ears or multiple ears at the same node. Symptoms may appear in patches within a field or across larger portions of a field.

red streaked corn leaves infected with corn stunt
Figure 2. Corn plants testing positive for corn stunt spiroplasma showed stunting, leaf reddening, and abnormal ears in (A) Erie County and (B) Jefferson County, New York near the end of the 2024 growing season.

How was corn stunt detected in New York?

From conference calls with my field crop pathology counterparts in southern and corn belt states this summer, I became aware that, in association with stunted and discolored corn plants, corn stunt and corn leafhopper were being observed further north of their usual ranges in 2024. Yet, I thought that New York was at a sufficiently northern latitude to avoid these problems. I credit a very observant agronomy specialist, Rafaela Aguiar with Kreher Family Farms, for noticing unusual symptoms in field corn in Erie County in late summer. Rafaela, a native of Brazil and with previous agronomic experience in South America, thought the symptoms resembled corn stunt which she had seen in South America. Though I was skeptical, it turned out that Rafaela was correct. We initially collected samples of symptomatic plants (Figure 2A) from three Erie County fields and sent them to the Diagnostic Lab at Oklahoma State University. Two of the three fields came back as strongly positive for the corn stunt spiroplasma. In a race against corn harvest and frost, samples were then collected from corn in other counties where similar symptoms had been reported. Samples from Jefferson, Monroe, and Yates Counties were also positive (Figure 2B). I suggest that, given more time for scouting in October, corn stunt may have been diagnosed in many more corn fields in New York this year.

What does this mean for future corn production in New York?

Documentation of the pathogen and its insect vector in New York in 2024 demonstrated that corn stunt could occur in New York in future growing seasons. And if spiroplasma-infected corn leafhoppers arrive at earlier corn growth stages, significant yield losses could result.  Then again, the atmospheric pathways that carried corn leafhoppers to New York in 2024 might not be repeated for several years. Many presume that the corn leafhopper will not overwinter as far north as New York, but, with climate change, that may be proven incorrect.  There is much that we don’t know. Cornell University, Cornell Cooperative Extension, and the New York State Integrated Pest Management Program have committed to participate in a Corn Stunt Working Group of plant pathologists and entomologists in states affected by corn stunt and corn leafhopper. One aim of the group is to deploy a common protocol to monitor the corn leafhopper during the 2025 growing season. Also, the Cornell Plant Disease Diagnostic Clinic is gearing up to offer a molecular test for corn stunt spiroplasma in 2025.

How will the corn stunt disease complex be managed?

Awareness and accurate diagnosis of corn stunt and regional monitoring for corn leafhopper are necessary first steps in managing this complex. Based on limited observations in 2024, it appears that corn stunt could cause significant yield reductions under New York corn growing conditions. Plant breeding is the long-term solution to prevent corn yield losses. Hybrids with moderate resistance to the spiroplasma and / or the leafhopper have been deployed in Latin American countries to manage the corn stunt complex. International companies that sell seed in the U.S. as well as Latin America are aware of which germplasms are most promising for incorporation into hybrids for northern temperate areas such as ours. I do not expect much choice of resistance in northern hybrids in 2025. Management of corn leafhopper populations with insecticides at corn vegetative stages to reduce corn stunt deserves further investigation. My principal advice to New York growers in 2025 is to plant corn at the earliest recommended date to avoid arrival of leafhoppers at the most vulnerable plant stages for infection by spiroplasma.

Acknowledgements:

I gratefully acknowledge agronomist Rafaela Aguiar of Kreher Family Farms for her keen observation of corn stunt symptoms and her continuing cooperation. Colleagues Michael Stanyard (Cornell Cooperative Extension Northwest New York Dairy, Livestock, and Field Crops Program) and Michael Hunter (New York State Integrated Pest Management Program) were instrumental in collecting corn leaf samples and leafhoppers from additional sites in New York. Identification of corn leafhopper and corn stunt spiroplasma would not have been possible without the expert help of colleagues at Oklahoma State University including professors Maira Duffeck and Ashleigh Faris, and diagnostician Jennifer Olson.

References:

Faris, A.M. and M. Duffeck. 2024. Corn leafhopper leads to corn stunt disease across Oklahoma – August 12, 2024. Oklahoma State University Extension News, EPP23-17.

Klaudt, J. 2004. Corn leafhoppers carrying corn stunt make first-time appearance in Kansas. Kansas State University Research and Extension News Release – October 16, 2024.

Redinbaugh, M.G. 2016. Diseases caused by mollicutes. Pages 16-19 in: Compendium of Corn Diseases (Fourth Edition), ed. G.P. Munkvold and D.G. White. APS Press, St. Paul, MN.

 

 

 

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PRE and POST Herbicide Options for Weed Control in NY Field Corn

Vipan Kumar1, Mike Hunter2, Mike Stanyard3

1School of Integrative Plant Sciences -Soil and Crop Sciences Section, Cornell University, Ithaca, NY 14853, 2Field Crops IPM Coordinator, New York State Integrated Pest Management Program (NYSIPM), Redwood, NY, 3Cornell Cooperative Extension Northwest New York Dairy, Livestock, and Field Crops Program

As the spring weather is warming up in the New York (NY), some producers have started planting their field corn in various parts of the state. Planting is an important time to make decisions regarding herbicide selection for effective weed control throughout the field corn growing season. This article provides an overview and discuss some major herbicide options labelled in the NYS field corn.

Preplant burndown options

If no tillage is practiced, burndown herbicides such as glyphosate (Roundup PowerMax), glufosinate (Liberty), paraquat (Gramoxone), 2,4-D (2,4-D LV4) and saflufenacil (Sharpen) can be helpful to control winter annual weeds prior to corn planting. If glyphosate-resistant horseweed is present in the field, paraquat or combination of Sharpen + 2,4-D can be an effective burndown option. Make sure to use appropriate adjuvants as per each herbicide label to maximize the effectiveness of these burndown treatments. Burndown treatments should be made on actively growing winter annual weeds under optimum weather conditions (sunny conditions with air temperature above 55 F with no forecast of cold weather after applications).

Preemergence (PRE) herbicide options

Preemergence or soil-applied herbicides are generally applied after crop planting but prior to its emergence. However, sometimes these preemergence herbicides can also be tank-mixed with preplant burndown treatments. Several preemergence options are available to use in field corn in the NY. Majority of these preemergence herbicides belong to Group 5, 14, 15, and 27 although there are few options from Group 2, 3, and 4 as well. Major preemergence herbicide options (not a complete list) along with their active ingredients and sites of action (SOA) labelled in NYS field corn are listed in Table 1. Several of these preemergence options are available in premixtures with two or three active ingredients from different groups (multiple SOA) and generally provide longer soil residual activity on summer annual weeds. For example, Harness Extra and FulTime NXT are premixtures of atrazine (Group 5) and acetochlor (Group 15) whereas Lumax EZ and Lexar EZ are premixtures of atrazine (Group 5), s-metolachlor (Group 15), and mesotrione (Group 27). Premixtures containing active ingredients from Group 5, 15 and 27 are most commonly used in field corn for grass and broadleaf weed control. While selecting appropriate preemergence option and its application rate, producers should thoroughly read the herbicide label for target weed species, rotational restrictions on the subsequent crops, cover crops or intercrops as well as consider the soil type, texture, and other soil properties (organic matter, soil pH, etc.).


Table 1.  Preemergence herbicide options labelled in NY field corn.

Herbicides Active Ingredients SOA
Prowl Pendimethalin 3
Aatrex Atrazine 5
Outlook Dimethenamid 15
Surpass NXT Acetochlor 15
Dual Magnum S-metolachlor 15
Harness Xtra, FulTime NXT Atrazine + Acetochlor 5, 15
Bicep Lite II Magnum, Cinch ATZ Lite Atrazine + S-metolachlor 5, 15
Verdict Saflufenacil + Dimethenamid 14, 15
Harness Max Acetochlor + Mesotrione 15, 27
Acuron Flexi S-metolachlor + Bicyclopyrone + Mesotrione 15, 27
Acuron Atrazine + S-metolachlor + Bicyclopyrone + Mesotrione 5, 15, 27
SureStart II Flumetsulam + Clopyralid + Acetochlor 2, 4, 15
Lumax EZ, Lexar EZ Atrazine + S-metolachlor + Mesotrione 5, 15, 27
Resicore, Resicore XL Clopyralid + Acetochlor + Mesotrione 4, 15, 27

*Restricted Use Pesticides      ¥Not for use in Nassau and Suffolk Counties


Postemergence (POST) herbicide options

Postemergence herbicides are applied after emergence of corn and weeds. Redroot pigweed, Powell amaranth, common lambsquarters, common ragweed, horseweed, common waterhemp, velvetleaf, foxtails (yellow, green, and giant), fall panicum, etc. are most common spring/summer annual weeds in NY corn. In addition, Palmer amaranth populations have also been recently found from six counties. In addition, field bindweeds, horsenettle, milkweed, yellow nutsedge, Canada thistle, hemp dogbane, quackgrass, etc. are most common perennial weeds. Johnsongrass populations have also been reported from corn fields in some southern counties of NY. Several postemergence herbicides are available to use in NY field corn to control these annual and perennial weed species. Majority of these labelled postemergence herbicides belong to Group 2, 4, 5, 6, 9, 10, 15, and 27.

Table 2 highlights major postemergence herbicide options (not a complete list) along with their active ingredients and sites of action (SOA) labelled in conventional, Roundup Ready and Liberty Link corn hybrids. Several of these postemergence herbicides are broad-spectrum and can control both grass and broadleaf weed species. For instance, Postemergence applications of Capreno, Realm Q, Impact Core, Roundup PowerMax, Liberty can all help controlling grass and broadleaf weeds. In contrast, postemergence applied Aatrex, Banvel, Clarity, Callisto, Yukon are most effective controlling broadleaf weeds only. Producers should thoroughly read each herbicide label for target weed species, rotational restrictions on the subsequent crops, cover crops or intercrops during selection of appropriate postemergence option and its rate. Make sure to use appropriate adjuvants as per each herbicide label to maximize the effectiveness of these postemergence herbicides. If glyphosate- or triazine-resistant weeds are present, producers should select alternative effective two-pass herbicide program (preemergence followed by postemergence).


Table 2. Postemergence herbicide options labelled in NY field corn.

Herbicides Active Ingredients SOA
For Conventional Corn Hybrids
Accent Q, Steadfast Q Nicosulfuron, Nicosulfuron + Rimsulfuron 2
Permit, Resolve Q Halosulfuron, Rimsulfuron + Thifensulfuron 2
Banvel, Clarity, DiFlexx Dicamba 4
Aatrex*¥ Atrazine 5
Basagran; Moxy 2EC Bentazone; Bromoxynil 6
Callisto; Armezone/Impact; Laudis Mesotrione; Topramezone; Tembotrione 27
Yukon Halosulfuron + Dicamba 2, 4
Capreno Thiencarbazon + Tembotrione 2, 27
Realm Q Rimsulfuron + Mesotrione 2, 27
Impact Core*¥ Acetochlor + Topramezone 15, 27
Kyro*¥ Clopyralid + Acetochlor + Topramezone 4, 15, 27
For Roundup Ready Corn Hybrids
Roundup PowerMax; Durango DM Glyphosate 9
Halex GT Glyphosate + S-metolachlor+ Mesotrione 9, 15, 27
For Liberty Link Corn Hybrids
Liberty Glufosinate 10

*Restricted Use Pesticides      ¥Not for use in Nassau and Suffolk Counties

Note: For further information on currently labelled PRE and POST herbicide options in NY field corn, check the 2024 Cornell Guide for Integrated Field Crop Management (available online).


Field Study in 2023

A field study was conducted in Franklin and Jefferson counties, NY, in 2023 growing season to determine the effectiveness of various preemergence herbicides (Table 3) with and without atrazine (42 fl oz/a) for weed control in field corn. Both field sites had natural infestation of common lambsquarters. Field corn was planted around May 20 at both sites and selected preemergence herbicides were applied immediately after planting. Small plots (10 feet wide by 30 feet long) were used to test each herbicide program. Test plots were laid arranged in Randomized Complete Block Design (RCBD) with 4 replications. All PRE herbicides were applied using CO2-operated backpack sprayer equipped with handheld boom with four nozzles (AIXR 110015). Results indicated no significant differences in common lambsquarters control among all tested preemergence herbicides at 35 days after treatments. Across both sites in Franklin and Jefferson counties, preemergence applied Acuron Flexi, Harness Max, Resicore XL, and Verdict + Outlook alone or with atrazine provided 94 to 100% control of common lambsquarters (Table 3; Figure 1)). In 2024, we plan to evaluate these preemergence applied herbicides (with or without atrazine) across multi-locations again to validate these results.


Table 3. Percent common lambsquarters control at 35 days after applications of various preemergence herbicide premixes alone or in combination with atrazine in field corn during 2023 growing season in Franklin and Jefferson Counties, NY.

 

Herbicide Active Ingredient (s) Site of action (SOA) Rate (oz/a) Franklin Jefferson
% control
Acuron Flexi S-metolachlor/bicyclopyrone/mesotrione 15, 27 72 98 97
Aatrex 4L + Acuron Flexi Atrazine + S-metolachlor/bicyclopyrone/mesotrione 5,15,27 42 + 72 99 94
Harness Max Acetochlor/mesotrione 15,27 64 100 97
Aatrex 4L + Harness Max Atrazine + acetochlor/mesotrione 5,15,27 42 + 64 99 97
Resicore XL Clopyralid/acetochlor/mesotrione 4,15,27 96 99 98
Aatrex 4L + Resicore XL Atrazine + clopyralid/acetochlor/mesotrione 5,4,15,27 42 + 96 100 99
Verdict + Outlook Saflufenacil/dimethenamid-P + dimethenamid-P 14,15,15 16 + 4.6 99 94
Aatrex 4L + Verdict + Outlook Atrazine + saflufenacil/dimethenamid-P + dimethenamid-P 5,14,15,15 16 + 4.6 + 42 99 98

corn rows showing amount of weeds with different treatments
Figure 1. Side-by-side comparison of PRE applied Acuron Flexi and Harness Max with and without atrazine for common lambsquarters control at 35 days after application in Jefferson County, NY during 2023 growing season.

Disclaimer: Brand names appearing in this publication are for product identification purposes only. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

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